The present invention generally relates to display devices, and more particularly to a thermoelectric display device which includes a liquid crystal material in thermally conductive relation with a thermoelectric element for providing variable optical states as a function of the current which passes through the thermoelectric element and consequently the temperature which is developed in the latter to which the liquid crystal material is exposed.
Liquid crystals are coming into wider use in display devices of various types. For example, liquid crystal displays are utilized in wrist watches, clocks, calculators, panel meters, multimeters, and industrial controls. The popularity of liquid crystals stems largely from the fact that they can store images and can provide color effects. Additionally, the circuitry for controlling the optical states of liquid crystals is relatively simple and the power levels involved are small. Liquid crystals and some of their applications are described in the following publications: "Liquid Crystals: Perspectives, Prospects and Products", by Edwin Stepke, Electro-Optical Systems Design, February, 1972, page 20; "Liquid Crystals - A Viable New Medium", by Brian Astle, Optical Spectra, July, 1973, page 35; and "Nematic Crystals Come of Age", by Donald H. Baltzer, Electro-Optical Systems Design, January, 1970, page 72 Liquid crystal displays are also discussed in the following U.S. Pat. Nos. 3,622,226; 3,687,515; 3,690,745; 3,772,874; 3,781,085; 3,781,863; 3,786,486; and 3,803,050.
The liquid crystal display devices described in most of the above-mentioned publications and patents utilize a current which flows through the liquid crystal material or an electric field applied across the same to alter the optically visible state of the liquid crystal material. Typically, the liquid crystal materials are optically variable between a transparent or light scattering visible state and, upon the application or removal of a predetermined field, to a second optically visible state wherein the liquid crystal is respectively light scattering or transparent.
An examination of the above references and patents discloses an inherent disadvantage in the semi-conductor display devices which utilize a conductive current or an electrical field to alter the optical states thereof. This disadvantage is in the construction of the display device which is generally complex in nature. Typically, two electrodes, one of which is transparent, are disposed to each side of the liquid crystal material. The arrangement and construction of electrodes results in a complicated structure insofar as manufacturing is concerned and this increases the cost of this type of display device.